The present invention generally relates to prosthetic implants and, more particularly, to femoral prostheses for knee joints, such as human knee joints.
It has become a common practice to implant medical prostheses to resurfaced articular surfaces of knees, for example, during knee replacement surgery. Many of the prior art prosthetic implants require large incisions to provide adequate access to the joint space to accommodate the implant as well as the surgical tools required during the surgery. In addition, conventional knee replacement procedures often involve resection or removal of substantial amount of bone or cartilage tissue in order to accommodate relatively large prosthetic implant designs typically used today. Such substantial removal of bone can cause increased surgical trauma to a patient and may increase time required for recovery and rehabilitation. In addition, excessive removal of bone tissue may lead to failure of the prosthetic implant due to subsidence thereof into the underlying bone tissue. Unfortunately, this often necessitates additional surgery, for example, revision surgery, in order to replace the failed implant.
Bone cement is typically used to secure implant components to a resurfaced bone. Misalignment of components may occur when too much or too little bone cement is placed on the implant and the implant positioned on the bone surface. If excess bone cement is used, bone cement may escape from between the bone and the edges of the implant requiring additional surgical steps or processes to remove the escaped cement. If the excess or leaked cement is left in the joint space after the surgery, the cement may cause irritation or even injury to the patient, necessitating revision surgery to correct. Alternatively, if too little bone cement is used, the inadequate amounts of bone cement may result in inadequate fixation of the implant to the bone, resulting in the loosening of the implant, necessitating revision surgery to correct.
Caspari et al U.S. Pat. No. 5,336,266 discloses tibial and femoral knee joint prostheses which include open channels through which bone cement can be passed to an inner surface of the implant to at least assist in fixing the implant to the tibia/femur bone. Caspari et al discloses a two piece tibial implant including a polymeric insert fitted into a metal implant body. Caspari et al employs a sharp rim on the implant to form a seal around the cement receiving chamber. In spite of such structure, the Caspari et al devices tend to have problems, for example, with cement leakage, too much or too little cement being injected, and uneven distribution of the cement, which can cause discomfort and/or other harm to the patient and/or revision surgery.
There is still an unmet need for better prosthetic implants, for example, femoral prosthetic implants useful in knee replacement surgery.